Conventionally, in the vibration generating machine or vibratory pile driving machine of this type, or the like, it has been general to use a vibration generating machine designed to generate vibrations by rotating rotary shafts having eccentric spindles (see, for example, Japanese Patent Publication 2003-300019 and Japanese Patent Publication 10-18288).
Incidentally, it is realized by various mechanisms as disclosed, for example, such as the one having one rotary shaft provided with an eccentric spindle as disclosed in Japanese Patent Publication 2003-300019, or the one having two rotary shafts parallel to each other having eccentric spindles as disclosed in Japanese Patent Publication 10-18288, or the one having a plurality of sets thereof.
The mechanism having two rotary shafts provided with eccentric spindle disposed parallel to each other is capable of setting the direction of vibration to be generated in a desired direction, and for example, in the mechanism disclosed in Japanese Patent Publication 10-18288, by cancelling the vibrations in the horizontal direction between two rotary shafts, it is intended to generate the vibration in the perpendicular direction only.